WORDS on WEATHER & CLIMATE

We had our first Ozone Action Day of the season last week, except they are now called Clean Air Action Days. According to the website of the West Michigan Clean Air Coalition, they are just “thrilled to announce that its Ozone Action program has now become the Clean Air Action program.” I guess they really get excited by this stuff. The change means we will now be getting Clean Air Action Days, not only in the summer due to ozone levels, but year round when fine particulate matter exceeds certain levels.

Fine particulate matter is defined as having a diameter of 2.5 micrometers or smaller. A single hair from your head is about 70 micrometers in diameter, which means a hair is 30 times larger than the largest fine particle. These particles are present in haze, smoke and pollution, and are small enough to enter the lungs, causing respiratory problems in some people. Thankfully, West Michigan doesn’t very often have a problem with fine particulate matter and ozone levels only reach unhealthy levels a few days each year.

Actions to lower ozone or fine particulate matter are voluntary at the current time. These actions include things I’m sure you’ve heard many times before, such as not mowing the lawn, not filling up your gas tank, or using a grill during the heat of the day, as well as curtailing driving. If air quality standards, which keep being strengthened, are not achieved by voluntary action, then the government will step in and mandate certain actions such as automobile emission inspections, which will be a cost to everyone.

We did set a record high temperature in Grand Rapids last week on June 7 at 94 degrees. It is the warmest temperature in June in the past two years but, more notably, it is the first time since 1953 that we have set a record high in June. Bill Steffen went back through the records and found out: “Most all of our summer season record high temperatures are old and not recent. If you take the months of June, July and August… those 92 days… only 14 days have record high temperatures that have been set or tied since 1959. The other 78 days all have record high temperatures from before 1960.”

Minneapolis also set a record high that day of 103 degrees, which is the warmest reading there since 1988. As a testimony to how cold the spring season was, in the nearby city of St. Paul, at 5 p.m. on June 7, the last of the winter snow piles finally melted in the parking lot of the Sears store. As a cold front dropped south across Lake Superior on June 7, the temperature at Munising, Mich. fell from 93 degrees to 57 degrees in less than one hour as the wind shifted from southerly to northerly off the lake.

Speaking of heat, there was another heat burst in the plains states on the morning of June 9. The temperature at Wichita, Kansas jumped from 84 degrees to 102 degrees in about a half hour and the humidity fell from 55% to 7%. This event happened a little after midnight.

A heat burst is a rare atmospheric phenomenon characterized by gusty winds and a rapid increase in temperature and decrease in dew point (moisture). Heat bursts typically occur during nighttime and are associated with decaying thunderstorms. We are not exactly sure what causes heat bursts but they are probably caused when rain evaporates in a parcel of cold dry air high in the atmosphere, making the air denser than its surroundings. The parcel descends rapidly and warms due to higher pressure at lower heights and reaches the ground at speeds frequently exceeding 50 mph.

Back in June 1960, a heat burst occurred near Waco, Texas that reportedly sent the temperature soaring from near 70 degrees to almost 140 degrees in the middle of the night, desiccating most of the vegetation in the area. There have been press reports from Portugal, Turkey and Iran telling of temperatures as high as 188 degrees, which actually turned asphalt to mush.

These extreme reports exceed the highest temperatures officially recorded on Earth, generally accepted as the Death Valley, Calif. report of 134 degrees and the Libya reading of 136 degrees. These heat bursts are not counted because (thus far) the worst heat bursts have been localized events, falling in-between local weather stations. I suspect they would be very scary events, especially in the middle of the night.

Craig James has been retired since July 1, 2008, after 40 years of broadcasting television weather. He was chief meteorologist at WZZM-TV for 12 years and chief meteorologist at WOOD-TV for 24 years. He is a graduate of Penn State University, where he received a Centennial Fellowship Award. He was also honored as a Fellow of the American Meteorological Society.

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